1. Field of Invention
The present disclosure relates to a power adapter. More particularly, the present disclosure relates to an energy-saving control device of the power adapter and an energy-saving control method.
2. Description of Related Art
A power adapter is generally used as a power conversion device for a power supply of a small-scale portable electronic device or electronic apparatus. The power adapter can be classified into an AC (Alternating Current) outputting manner and a DC (Direct Current) outputting manner according to its outputting type, or into a plug-in and a desktop according to its connection manner. In human daily life, especially, the power adapter having the DC outputting manner is more widely applied, such as an electronic device like a cordless-and-base telephone, a game console, a language repeater, a personal stereo, a notebook computer, a tablet computer and a cellular telephone.
In the prior art, in order to reduce the energy consumption of the power adapter, the core component (such as, the power converter) of the power adapter is often operated in a hiccup mode under a no-load condition. Generally, if the electronic device is electrically connected with the power adapter, it represents that the power adapter has carried a load; and when the electronic device is separated from the power adapter, it represents that the power adapter doesn't carry the load or the power adaptor is in a no-load state. Therefore, detecting the load of the power adapter is an important step for achieving energy saving. Currently, there are two typical load detection to manners. One is to detect a voltage signal from an ID pin of a cable interface, so as to determine whether a connection cable in the power adapter is plugged into an electronic device. For example, when the voltage on the ID pin is a low level, the detection circuit sends a control signal to the PWM controller for enabling the power converter to be operated at a normal working mode. Once the voltage on the ID pin is changed to a high level, the detection circuit sends another control signal to the PWM controller for switching the power converter from the normal working mode to the hiccup mode, thereby achieving the energy-saving effect. The other is to detect a resistance value between a voltage pin and a ground terminal, thus determining whether the power adapter is removed from the electronic device in accordance with the detected resistance value. However, no matter which of the aforementioned manners is used, a lot of electronic components are required and more layout space on a printed circuit board (PCB) is occupied, thus increasing the manufacturing cost of the power adapter.
In view of this, many in the industry are endeavoring to find ways in which to design a novel power adapter, so as to detect whether the power adapter is electrically separated from the electronic device with low cost, and thereby adjusting the working mode of the power converter to achieve the energy-saving purpose.